v1.0.8

• PDF trailer was missing the /ID entry required by PDF/A-3. ISO 19005-3
  (and PDF 1.7 §14.4) require the trailer dictionary to carry an /ID array of
  two byte strings: the first immutable identifier of the original document,
  the second updated on every modification. pdf-lib initializes
  trailerInfo = {} and never writes one on save, so veraPDF and the FNFE-MPE
  Factur-X profile rejected every PDF this library produced as non-conformant.
  Added ensureIdTrailer in src/core/embed.ts which runs after the first
  pdfDoc.save() when addPdfA3Metadata is on: it computes an MD5 over the
  serialized bytes (per PDF 1.7 §14.4 — uniqueness, not cryptographic strength,
  is what matters), preserves any pre-existing first identifier, and writes the
  pair before re-saving. Regression tests added in tests/embed.test.ts
  covering both the no-existing-trailer and existing-trailer paths (thanks
  @sco-indy, #3).